Hi there @Cuongnguyen!
Ivy here from Shopify.
An apps policy for paused stores will vary from app to app, some may charge despite the pause and some may not. It is for this reason that I always advise removing an app before store pause to be 100% sure you are not being charged, or at least emailing the app developers to check what their policy would be in this case.
Can I ask why you have chosen t pause your store? I'd love to help you out with some business growth ideas - how do you feel things are going at the minute? Is there anything you'd like to improve or change?